You can most certainly convert to an ATPL after you meet the Experience, Skill and Knowledge requirements, yes ABY has to authorize it and in most cases they will. It might not happen at 1500 but it will be done along with the next PC. Many have gotten their ATPLs and many have left for EK and QR.
On the other hand the MPL training can take quite sometime, AA is not reliable and ABY will call the shots as to when they are ready to start and finish your training and most importantly give you employment afterwards.
Its still the best way to get on to the right seat. Yes there are CPL and fATPL holders getting on to airlines right away in Europe but its rare. I dont see those flight time requirements going down just as yet.